<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    div {
        position: absolute;
        left: 50%;
        top: 50%;
        width: 200px;
        height: 200px;
        transform: translate(-50%, -50%);
        background-color: #bfa;
    }
</style>

<body>
    <div>

    </div>
</body>

</html>